Disallow related elements to be treated as choices

DRF will try to resolve potential candidates into the OPTIONS endpoint.
This is mainly to support their POST field in the browseable API.   We
don't need this and it can yield some expensive queries so we bypass
generating choices for any RelatedField fields

awx/api/metadata.py

@@ -1,6 +1,8 @@
 # Copyright (c) 2016 Ansible, Inc.
 # All Rights Reserved.
 
+from collections import OrderedDict
+
 # Django
 from django.core.exceptions import PermissionDenied
 from django.http import Http404
@@ -10,6 +12,7 @@ from django.utils.encoding import force_text
 from rest_framework import exceptions
 from rest_framework import metadata
 from rest_framework import serializers
+from rest_framework.relations import RelatedField
 from rest_framework.request import clone_request
 
 # Ansible Tower
@@ -37,9 +40,20 @@ class Metadata(metadata.SimpleMetadata):
         return field_info
 
     def get_field_info(self, field):
-        field_info = super(Metadata, self).get_field_info(field)
-        if hasattr(field, 'choices') and field.choices:
-            field_info = self._render_read_only_choices(field, field_info)
+        field_info = OrderedDict()
+        field_info['type'] = self.label_lookup[field]
+        field_info['required'] = getattr(field, 'required', False)
+
+        text_attrs = [
+            'read_only', 'label', 'help_text',
+            'min_length', 'max_length',
+            'min_value', 'max_value'
+        ]
+
+        for attr in text_attrs:
+            value = getattr(field, attr, None)
+            if value is not None and value != '':
+                field_info[attr] = force_text(value, strings_only=True)
 
         # Indicate if a field has a default value.
         # FIXME: Still isn't showing all default values?
@@ -48,21 +62,18 @@ class Metadata(metadata.SimpleMetadata):
         except serializers.SkipField:
             pass
 
+        if getattr(field, 'child', None):
+            field_info['child'] = self.get_field_info(field.child)
+        elif getattr(field, 'fields', None):
+            field_info['children'] = self.get_serializer_info(field)
+
+        if hasattr(field, 'choices') and not isinstance(field, RelatedField):
+            field_info['choices'] = [(choice_value, choice_name) for choice_value, choice_name in field.choices.items()]
+
         # Indicate if a field is write-only.
         if getattr(field, 'write_only', False):
             field_info['write_only'] = True
 
-        # Update choices to be a list of 2-tuples instead of list of dicts with
-        # value/display_name.
-        if 'choices' in field_info:
-            choices = []
-            for choice in field_info['choices']:
-                if isinstance(choice, dict):
-                    choices.append((choice.get('value'), choice.get('display_name')))
-                else:
-                    choices.append(choice)
-            field_info['choices'] = choices
-
         # Special handling of inventory source_region choices that vary based on
         # selected inventory source.
         if field.field_name == 'source_regions':